Electric vacuum-tube device and the like



Aug. 10 1926. 1,595,870 E. Y. ROBINSON ELECTRIC VACU UM TUBE DEVICE ANDTHE LIKE Filed March 2 1924 3 SheeFs-Sheat 1 Q I 7107' 23 z'zza Aug. 101926. 1,595,870

E. Y. ROBINSON ELECTRICVACUUM TUBE DEVICE AND THE LIKE Filed March 19243 Sheets-Sheet 5 Patented Aug. 10,1926.

' UNITED STATES PAT NT OFFICE.

,- EBNE ST ROBINSON, OF CHESTER, ENGLAND, ASSIGNOB TO METROPOLI-TAN-VICKERS ELEGTRIGAL COMPANY LIMITED, 0]? LONDON, ENGLAND, A

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BRITISH ntnc'rnro vacuum-rune DEVICE sun was: mm.

. Application flied March 29, 1923, serial Eoi 702,907, and in EnglandApril 27,1923.

This invention relates to vacuum electric devices such .asthermionicvalves, and the like and more especially to such devices which arecooled during operation by means of fluid circulation, the inventionbeing also applicable to valve devices which are continuously exhaustedduring operation by means of a vacuum pump such as a mercury vapour pumpwhich is fluid cooled. In such devices it is essential that the supplyof cooling fluid such as water should not tail 'since' in the one casethe, part of the valve which is being cooled such as the anode would beoverheated, and in the other casethe vacuum would fail.

An object of the present invention isNto provide means responsive to thecondition of the supply .of'cooling fluid for protecting the vacuum tubeor valve device against operation under undesirable conditions of saidsupply.

' of the invention is to provide protective means which upon theoccurrence of undesirable condltions of the normal fluid supply effectthe connection to the'tube valve or -*,pump of a supply of cooling fluidfrom a to valves in which the anode is operated reserve or stand-bysource. In addition the protective means may effect the operation ofa-wa-rning device such as a signal light or bell. Furthermore,protectivemeans may be provided for stoppingthe operatign of t e valves,such as by cutting offvthe'anode -o the cathode supply, in caseundesirable conditions in the auxiliary supply should.

: also arise.

The invention is particularly applicable as-described. in thespecification of my copending'application, Serial No. 699,185, filedMarch 1 1924, in which case itjs not neces- .sary to employ means toprovide an insulatconstructed vof insulating materi 9. ta ged to beo'10ng .f lat ing column of cooling liquid between the source of thecooling liquld and the valve, It may, however, be applied to valves-inwhich the anode is not operatedat; earth potential, either by arranginglthat the cool-I .ing liquid is one having a ig insulation resistance,suchfor efzamgple. as pll, or else when water is en'ip oyeespecially'jwater which is taken a water main it'niay be arranged thatthe inletand outle 1 parts, particula More specifically, the object vtial are supplied with current froihaudirect Y resistance column ofwateris interposed between the anode and earth. This is of course a wellknown arrangement which has frequently been used to insulatewater-cooled from earth.

Toenable the invention to be clearly une derstood it wi nowloe'described withreferenceto the ace mpanying drawings in which rly ofvacuum tube devices,

Fig. v1 is a diagrammatic representation of a vacuum tube protectivesystem in accordance with the invention, Figs. 2 and 3 are sectionalelevations of two forms of pressure relay, Fig.- 4 is a sectionalelevation of a cooling jacket with a thermal relay, Fig. 5 is asectional elevation or" another iorm of pressurerelay, and Fig. 6 is adiagrammatic representation of arrangements giving further-protection incase the auxiliary sup' plyshould also fail.

Referring first to Fig. 1, this illustrates an application of theinvention to a threephase half-wave rectifier, the valves 1 being of thetype wherein a portion of the envelope is formed of metal, which portionconstitutes the anode 2 which duringoperation is fluid-cooled. For thispurpose it 'is placed in a jacket 3 through which water or othervcoolingfluid from a supply main 93,

' for example, is passed by means of inlet and fectively insulated fromearth. 9 The cathodes which. operate-substantially at earth-potencurrentgenerator 87through a switch 88 and a rheostat 89, the cathodes in thisinstance beingof the type which are heated by the passage therethroughof an: electric current." The anodes are. supplied with three-phasealternating current from a'starconnected secondary winding of a trans-'-former 86 the, primary of which isjonnected. with a three-phase supply.The valves 1- supply rectified alternating current to't he outputcircuit 90. 'Between thesupply main 93 and thecooling system'there isprovided a manually o erable valve 94am an elecg trically opera 'le'valve 95; the control of;

.which latter "will behereinafter described.

' 'f'The outlet water from-the valves p to receive energy from a batteryor other. a

when the flow of cooling fluid is normal.

through pressure relays 96 which may assume any ofthe forms hereinafterdescribed 1 and Which are connected electrically in series of which isadapted to cooperate with two pairs of contacts. When coil 99 of therelay 98 is energized the upper pair of contacts is bridged by thearmature whereby a coil 100 and a second coil 101 in series connectiontherewith are energized from a suitable source of current 102. Thesecond coil 101 controls the operation of a valve 103, provided in apipe connection between an auxiliary supply of Water 104 and the inletpipes 91. The normal condition of the relay 98 when the Water cooling isadequate is with the coil 99. energized and the upper contacts thereofclosed. Under these circumstances the electrically operated valve 95 isopen by reason of the energization of the coil 100 and the auxiliaryvalve 103 is closed by energization of its operat-- ing coil 101. Thelower contacts of the relay 98 control the operation of a signallingdevice such as an electric bell 105 adapted source 106.

With'the system above described suppos-' ing that durin the rectifyingoperation the water supply rom the main 93 should fail or fall below apredetermined minimum, such that the electric circuit through one ormoreof the'pfessure relays 96 is broken,

' the armature of the relay 98 will fall. so that the valve operatingcoils 100 and 101 will be de-energized whilst the circuit of theelectric bell 105 is closed to provide an audible signal. Thede-energization of the coils 100 and 101 will efiect the closure of thevalve 95 and the opening of the valve v103 and in this manner the mainsupply of cooling fluid is cutoff and the auxiliary supply 104 broughtinto' operation. To obtain a suitable pressgre head for-the operation ofthe relays 96, constrictions 108 may be provided between the said relaysand the discharge pipe 107. c

When the valves are continuousl evacuated during operation by means 0 aWater cooled pump such for example as a pump of the Langmuintype similarmeans may be provided for protecting the system against failure of thesupply. of cooling fluid to the pumps. The relays of such additional protective systems may be connected electrically in series with the relaysofthe system illustrated in Fig. 6. Furtnermore when the valve iscontinuously evacuated during operation failure of the water supply willresult in an increase in temperature of the anode which in turn willcause gas to be given off therefrom and render the valve soft, as analternative type of relay a gas pressure gauge may be connected withthevalve and arranged to operate a relay. For example an ionizationgauge maybe employed which when the gas pressure in the Valve risesabove a predetermined maximum will operate a protective relay. Suchionization gauge may be connected Wth the interior of the valve and thecircuits of the gauge may be so arranged that when the positive ionic.current collected by the electrodes exceeds a predetermined amount, therelay is tripped and the necessary protection eifected.- Alternatively,a relay of the thermostat type may be employed that will be hereinafterdescribed. 7

Referring to Fig. 2 which illustrates one form of the relay 96 indetail, the U-tube 30 is formed of glass and partially filled withmercury and is connected to a T-branch 31 of the outlet pipe'92 by meansof a rubber sleeve 32 or otherwise. The tube 30 is provided with bulbsor enlargements 33 and 34 for a purpose to be hereinafter explained. Oneof the gontact electrodes 35 .is inserted in thelower part of the U-tubewhilst the other contact electrode. 36 is inserted therein at a higherlevel which depends upon the pressure in the portion 20 of the outletpipe tion with Fig. 2 but the U-tube 40 is of metal such for example assteel whereby a more robust construction is obtained. The upper end ofthe U-tube 40 is enlarged at 41. The other end thereof is secured to aplug 42 which is in turn secured within the end of a reservoir 43'whichis connected to the T-connection 44 of the outlet pipe by means of aunion 45. The reservoir 43 is provided with a plug 46 .by means of whichthe mercury may be introduced into the tube. The enlarged portion 41 ofthe U-tube 40 is secured to the base of the second reservoir 47 theupper end of which is provided with a cap 48 which supports a metal bushnut 49 insulated from the cap 48 by means of bushes and washers 50 ofinsulating material. A screw-threaded metal rod 51 passes through thebush 49 and is provided with external terminal nuts as shown. The metaltube 40 constitutes one electrode of the'device whilst the rod 51constitutes the other electrode. The rod 51 may be spaced from the metaltube 40 by means of a fibre Washer 52 which the bush 49.

" portion 41 of the tube.

rubber ring which is clamped between the .end of the jacket 3 and acap-ring 56 which has screw threaded engagement with the jacket 3. Thewater entering by the in let pi e 4: and leaving b the pipe 5 is given abig velocity throug the jacket by the provision-therein of an annularmember 57 Electricalconnection between the anode 2 and jacket 3 is--provided by means of the flexible member 58. A glass tube 59 having abulb 60 at one end 1s inserted through aligned openings in the jacket 3and member 57 so that the bulb projects into the path of the coolingfluid passing through the -jacket.' The tube-59 c0nta-ins a body ofmercury'and is provided with a contact 61 which .is always immersed inthe mercury and. a second contact 62 which becomes immersed in themercury when the. latter rises within the normally unfilled portion ofthe tube 59.

due to the heat in the jacket 3 after the manneroth thermometer. Theupper electrode 3 62 is so located within the tube that when thetemperature of the bulb 66'exceeds a predetermined limit the contacts 61and 62 which are connected with the protective gear as described inconnectirgn with Fig. 1 are connected, together by the mercury. In thiscase, however, the contacts on the relay controlled by the coil 99willbe altered so that they are normally closed instead of beingnormally opened as illustrated in Fig. 1. -.-'lhe thermal device ispreferably removably mounted in the jacket and to this end it is vsecured in a metal sleeve 64 having a conical nectedto'the supply pipeof t e water jacket of thewalveor the diffusion pump asthecase may be bymeans of the perforatedcap 7-1 and the union 72-. A n accurately fittingpiston '73 operates wi'thiirthe cylinder 70 such piston preferabl%ifiange 65'where'by itmay be securedin pos tion by the flange nut orunion 66.. The vertical portion of the tube is protectedagainstdamaged-lid mechanical shock by means of. a metal cover which isconstructed in twoii parts 67 and .68 as shown, the latter of which?parts is soldered or otherwise;- permanently connected with the metal:tube 64 whilst the portion 67 is tubular and arranged to vfit upon andaround the portion68.v The con-:

ductors connected with the electrodes 61 and 62 pass through a gland 69.

' Ehe modified form .of p'ressure rela illus-j trated in Fig. 5comprisesa linden 0 conhaving: a on leather as indicated rat-17 t, -hegp nrg iss e:

nectedwith. a pivoted 7 5 through a v or other parallel motion 76. Thearm 7 5 carries a relay contact member 77 which cooperates with a secondcontact member 78 mounted upon but insulated from a bracket 79 which maybe secured to the cylinder 70.

The contacts are normally retained separated by means-of a spring 80. Inoperation the water pressure acting on the underside of the piston 70tends to close the contacts 77 and 78, thus controllingthe protectivegear in a manner similar to that previously described In the event ofthe water pressure ,fallingbelow a. predetermined minimum the contactsopen whereby the anode and cathode currents may be cut 0d oralternatively a reserve or stand-by source of cooling water connected tothe jacket. The contants 77 and 78 may control the operation of thecontactor switch 26 directly "that is to say, the intermediate relay 21of Fig. 1 may be omitted.

Referring now to Fig. 6, which illustrates how protection against theoperation of a valve may beprovid'ed in case the auxiliary supply alsofails, the valve lis of the three electrode type and the anode isoperated at earth potential in the manner described in the specificationof my co-pending'application, Serial No. 699,185, tiled'll/ larch 1a,192%, and the valve is arr-tugged to generate oscillations. in acircuit-sue as the antenna 6. Power is supplled to the valve by meanstive terminal of which is connected to the anode 2 and also to earth.Asshown, the

generator 7 may be connected to the water .'acket 3 to which the anode 2is connected y means of a flexible or resilient conductor.

of the direct current generator 7 the posi- 8.. The anode current passesthrough the? anode coil 9 which is coupled to the antennacoil'andjthence passes to the cathode ct the valve. .The grid couplingcoil is indicated."

at 10. In the present instancethe valve 1 has-a cathode of the typedescribed in the specification'of my copending applicat on,- Seria'i'No.653,544,; ifiled 24th July, 192:} a and eon'sistsof two' metallic tubesmounted onewithin the other of which the inner tube'is at negativeotentiaLwith respect to the outer tube so t at heating space currentflows from theinner tube to the outer tube. The cathode isbrought untothe tem rature at which it-will maintain itself due- 4 the spaceciirrent between its per tions by means ofan auxiliary filament cathodewhichfis mounted within the inner '1 tube. In Fig.1 the conductors 1.1supplyi current to" the auxiliary filament cathode and'theconductors 12are connected to the aforesaid tubular portion of the cathode. The,heating space current is supplied by 12. g The current for; the filamentthe generator 13 whichis connectedthrough p a the variable resistance14jtothe conductors cathode is supplied from the gendrator 13 through afixed resistance 15 and a variable resistance 16 in series therewith.

The outlet pipe 92 from the water jacket 3 has connected to it apressure relay 96 which may be in the form of a U-tube con- .tamlng abody of mercury as illustrated in Figs. 2 and 8. Said tube is providedwith two electrodes 18 and 19 which areso arranged that when the coolingfluid is flowing the mercury establishes connection between them owingto the pressure head in the portion 107 of the pipe which is remote fromthe relay 96 and jacket 3. When the electrodes 18 and 19 are thusconnected together by the body of mercury the relay coil 99 is energizddfrom a suitable source of current such as a battery 97 andthe-energization of the coil 99 operates a contact member 23 to bridgethe relay contacts 24 thereby effecting the energization of theoperating coil 25 of a contactor. switch 26 h from a suitable source ofcurrent 102. The energization of the coil 25 causes the contactor switch26 to close and complete the circuit by which a heating current issupplied to the cathode of the valve 1, this circuit passing through amanually operated switch 28 the function of which will be hereinafterdescribed. With this arrangement it will be observed that unless apredetermined pressure obtains within the portion 20 of the outlet pipethe contactor switclr26 will open after a time interval, whereupon thesupply of current to the valve is cut 'ofi. Furthermore, in the event ofthe supply of water falling below a predetermined amount the pressurewill fall and the 'contactor switch will be opened as above described sothat both the anode current and cathode current are automatically cutofl.

In order to start the operation of the cathode the switch 28 is presseddownwards whereby 'the auxiliary cathode is supplied with heatingcurrent and at the same time the inner "tube of the cathode is madepositive with respect to the auxiliary cathode. The resistances 15and'16 provide such a voltage drop as to make the inner tubesufficiently positive with respect to the auxiliary cathode. Heatingcurrent from the generator .13 passes from the auiliary cathode to theinner cathode tube which isadditionally heated by radiation-from theauxiliary cathode. When the inner cathode tube is raised to asufficiently high temper ature the switch 28 is moved to its upwardposition whereby a potential difference is established between the innerand outer cathode tubes and at the same time the supply of heatingcurrent for the auxiliary cathode is cut off. The generator 7 whichsupplies the anode current is connected to the positive terminal of thecathode heating system. A condenser is connected across the generator 7in order to pass the high frequency com onent of the anode current.

Whilst in t e above described arrangement the valve is provided withcathodes which are heated as described in the specification of myco-pending application, Serial No. 699,185, filed March 14, 1924, itwill be understood that the cathode may assume other forms and may beheated in a ditlerent manner arid also that the source of directcurrentfor the anode may be a thermionic rectifier or battery of accumulators.

Alternatively to the above described arrangement it may be arranged thaton operation of the relay the anode current only is cut off or both theanode and the cathode heating currents may be cut oil by respectiveswitching devices. When the gap between the anode and cathode is largeit will generally be sufficient to interrupt the anode Ell current onlybut when the gap is relatively the electrical circuit is made instead ofbroken, in which case said relays will be connected in parallel with oneanother, with the battery or source of current and with the operatingcoil of the water valve controlling relay.

' I claim as my invention:

1. In an electrical system, the combination with a vacuum electric tubedevice having a part thereof which is adapted to be fluid cooled duringoperation, and a supply of cooling fluid therefor, of an auxiliarysupply of cooling fluid, and means which be come operative to connectsaid auxiliary supply to the system when the condition of thefirst-mentioned supply of cooling fluid becomes undesirable.

2. In an electrical system, the combination With a vacuum electric tubedevice having a part thereof which is adapted to be fluid cooled duringoperation, and a supply of cooling fluid therefor, of an auxiliarysupply of cooling fluid, and a fluid pressure operated relay adapted toconnect said auxiliary supply to the system when'the fluid pressure ofthe latter falls below a predetermined value.

3. In an electrical system, the combination with a vacuum electric tube,device havin a part thereof which is adapted to be fluid cooled duringthe operation, and a supply of cooling fluid therefor, of an auxiliarysupply of cooling fluid, and a relay controlle by weaero the dischargepressure of the cooling fluid to control the connection of saidauxiliary ply of cooling fluid, and means which become operative toconnect said auxiliary supply to the system when the condition of thefirst-mentioned supply of cooling fluid becomes undesirable, and meansfor protecting the system against operation when the condition of thesupply of cooling fluid is undesirable.

5. In an electrical system the combination with a vacuum electric tubedevice having an anode thereof which is maintained at earth potentialand is adapted to be fluidcooled during operation, and a supply ofcooling fluid therefor, of an auxiliary supply of cooling fluid, andmeans which becomes operative to connect said auxiliary supply to thesystem when the condition of the main supply becomes undesirable.

6. In an electrical system, the combination with a plurality of vacuumelectric tube devices having parts thereof which are adapted to be fluidcooled during operation, and a supply of cooling fluid therefor, of anauxiliary supply of cooling fluid, and a vplurality of relays responsiveto fluid pressure in the system for connectin said auxiliary supply whenthe conditions m the firstmentioned supply become undesirable, saidrelays being connected electrically in series.

In testimony whereof I have hereunto subscribed my name this 18th day ofMarch, 1924.

ERNEST YEOMAN ROBINSON,

